1. Field of the Invention
The present invention relates to a tracking error detection system for detecting tracking errors in a magnetic recording/reproducing apparatus for recording/ reproducing digital signals.
2. Description of the Prior Art
Conventionally, in a tracking error detection system used in home-use VTR sets, a control track is provided in the longitudinal direction on a magnetic tape, separately from a video track on which recording/ reproducing of video signals are effected, so that pulses indicating a rotational phase of a head drum are recorded as a control signal on the control track, whereby, in reproduction, the phase of a reproduced control signal is compared with that of the pulses indicating rotation of the head drum to thereby detect a tracking error. (For example, reference is made to "VTR Technology", supervised by Ryo Takahashi, Japan Broadcasting Corporation (NHK)).
On the other hand, in a tracking error detection system used in 8 mm videos, four low-frequency pilot signals different in frequency from one another are established and those four low-frequency pilot signals are recorded one by one on every video track so that every pilot signal is frequency-multiplexed with a video signal on the track. In reproduction, two low-frequency pilot signals recorded on two adjacent video tracks are detected as cross-talk from adjacent video tracks and a power difference between the two detected low-frequency pilot signals are compared with each other to thereby detect a tracking error.
In such a conventional method using a control track, however, it is impossible to detect the linearity of a recording track and it is very difficult to improve the accuracy in tracking error detection.
In the tracking error detection system used in 8 mm videos, on the other hand, it is possible to detect the linearity of the video track, however, the frequency-multiplexing of a low-frequency pilot signal with a digital video signal causes a problem that the pilot signal acts as a disturbance against the digital signal because such a digital signal used in a digital magnetic image recording/reproducing apparatus includes signal components even in a low frequency band.